This invention relates to an osteogenic osteoimplant made up of, at least in part, elongate bone-derived elements intended for use in the repair, replacement and/or augmentation of various portions of animal or human skeletal systems. More particularly, this invention relates to an implant made up of a mass of elongate bone-derived elements optionally in combination with bone powder. The elongate bone-derived elements and/or bone powder may be nondemineralized bone, partially or fully demineralized bone or any combination of the foregoing. An implant of the invention herein is especially suitable for use in periodontal applications, e.g., guided bone regeneration; plastic and reconstructive surgery, e.g., where the contour of the bone must be modified; and filling of cranial defects; though other skeletal applications are also envisioned.
The use of pulverized exogenous bone growth material, e.g., derived from demineralized allogenic or xenogenic bone, in the surgical repair or reconstruction of defective or diseased bone is known. See, in this regard, the disclosures of U.S. Pat. Nos. 4,394,370, 4,440,750, 4,472,840, 4,485,097, 4,678,470, and 4,743,259; Bolander et al., “The Use of Demineralized Bone Matrix in the Repair of Segmental Defects”, The Journal of Bone and Joint Surgery, Vol. 68-A, No. 8, pp. 1264-1273; Glowacki et al, “Demineralized Bone Implants”, Symposium on Horizons in Plastic Surgery, Vol. 12, No. 2; pp. 233-241 (1985); Gepstein et al., “Bridging Large Defects in Bone by Demineralized Bone Matrix in the Form of a Powder”, The Journal of Bone and Joint Surgery, Vol. 69-A, No. 7, pp. 984-991 (1987); Mellonig, “Decalcified Freeze-Dried Bone Allograft as an Implant Material In Human Periodontal Defects”, The International Journal of Periodontics and Restorative Dentistry, pp. 41-45 (June, 1984); Kaban et al., “Treatment of Jaw Defects with Demineralized Bone Implants”, Journal of Oral and Maxillofacial Surgery, pp.623-626 (Jun. 6, 1989); and, Todescan et al., “A Small Animal Model for Investigating Endosseous Dental Implants: Effect of Graft Materials on Healing of Endosseous, Porous-Surfaced Implants Placed in a Fresh Extraction Socket”, The International Journal of Oral & Maxillofacial Implants Vol. 2, No. 4, pp. 217-223 (1987).
More recently, processed bone has been developed into new shapes for use in new surgical applications, or as new materials for implants that were historically made of non-biologically derived materials.
U.S. Pat. No. 4,678,470 describes a non-layered osteoimplanting material produced from bone by a process which includes tanning with glutaraldehyde. The bone may be pulverized, used as a large block or machined into a precise shape. The tanning stabilizes the material and also renders it non-antigenic but negatively impacts the osteoinductivity of the product. The bone material may also be demineralized.
U.S. Pat. No. 5,464,439 describes a continuous sheet of completely or partially demineralized natural bone having sufficient flexibility to conform to the implant site.
U.S. Pat. No. 5,556,430 describes the use of a continuous sheet of demineralized bone or partially demineralized bone, however, the sheet must be sufficiently flexible, therefore sacrificing strength, in order to conform to the skeletal site to which it is applied.
U.S. Pat. No. 5,507,813 describes a surgically implantable sheet formed from elongate bone-derived elements, optionally demineralized, containing biocompatible ingredients, adhesives, filler, plasticizers, etc.
U.S. Pat. No. 4,932,973 describes an artificial organic bone matrix with holes or perforations extending into the organic bone material. These holes or perforations are indicated to be centers of cartilage and bone induction following implantation of the bone matrix.
U.S. Pat. No. 4,394,370 describes a one-piece sponge-like osteoimplant material fabricated from fully demineralized bone powder or micro particulate bone, and reconstituted collagen. The sponge-like graft is optionally cross-linked with glutaraldehyde.
Another one-piece porous implant is described in U.S. Pat. No. 5,683,459. The implant is made up of a biodegradable polymeric macrostructure, which is structured as an interconnecting open cell meshwork, and a biodegradable polymeric microstructure composed of chemotactic ground substances such as hyaluronic acid.
U.S. Pat. No. 5,899,939 describes an osteoimplant fabricated from a number of layers possessing compression strength characteristics approximating those of natural bone.
However, the prior art demineralized bone products have proven to be unsatisfactory for applications requiring a thin osteogenic material capable of displaying a variety of properties. In one embodiment of the invention herein, the material is thin and conforming, i.e., able to be shaped closely to the exterior of bony surfaces, thereby minimizing stress on the overlying soft tissues. In a different embodiment of the invention herein, the material is form holding, i.e., able to maintain its three-dimensional architecture even after rehydration and deformation prior to or during implantation. Moreover, prior art products have been limited as to the size and shape of the finished product by the size and type of starting material used to form the product. In every embodiment of the invention herein the size of the implant is limited only by the total amount of starting material available and not by the size and type of starting material. Thus, a thin osteogenic material capable of displaying a variety of properties would be highly desirable.